The mounts are indeed 3M one time use double sided tape.
This is the front upper bumper, but they look like this (generally)
If you feel they are falling in, you could check the tape isn't pulled away on the backside. If so, a dab of glue between? Or order a new mounting bracket (I want to say they are something around $20 each without the sensor)
I would suggest having the dealer fix it if the truck is still under warranty. If you fix it yourself then have a more serious sensor problem they could claim it’s now out of warranty.